To reduce noise emissions by a gas-carrying line, e.g., an exhaust line for an internal combustion engine in which the gas flow also carries airborne sound, it is known that a muffler of the type defined above can be installed in this line. The muffler preferably has gas that is conveyed in the line flowing through it. At the same time as the gas, the airborne sound entrained by the gas also enters the muffler, where it is dampened by reflection, resonance and sound-absorbing materials, for example. The dampening of airborne sound is also of great interest with other gas-carrying lines, e.g., in a fresh air system of an internal combustion engine, so that the present invention should fundamentally not be limited to use in internal combustion engines.
If hot gas is carried in the line in which the muffler is arranged, e.g., in an exhaust line of an internal combustion engine, then thermal stresses necessarily occur and must be compensated via suitable countermeasures. A known countermeasure here is the arrangement of a sliding seat which allows an axial equalizing movement of two pipes inserted one into the other in the area of the sliding seat. In addition, it is customary to reinforce the housing of such a muffler with at least one inside plate through which the inside pipes must be guided, depending on the gas guidance in the interior of the muffler. The inside plates here also serve to secure the pipes in the housing. It is conventional to mount one pipe on a first inside plate in the vicinity of the sliding seat and the other pipe on a second inside plate or on a housing wall which is spaced a distance away from the first inside plate. However, the design of such a sliding seat and its connection to an inside plate of the housing are complicated and expensive.
DE 10 2004 054 441 describes a muffler in which two inside pipes are mounted on one and the same inside plate, and to this end, at least one spring-elastic first tongue attached to the first inside pipe and at least one spring-elastic second tongue attached to the other inside pipe are designed on this inside plate and the second tongue is movable with spring elasticity independently of the first tongue. Due to this design, the spring-elastic tongues can conform to the thermally induced changes in length of the inside pipes independently of one another without resulting in unacceptably high stresses inside the inside plate.